diff --git a/expo/scripts/visualize_experiment.py b/expo/scripts/visualize_experiment.py
index 940d1f11b..42b4490ec 100644
--- a/expo/scripts/visualize_experiment.py
+++ b/expo/scripts/visualize_experiment.py
@@ -19,5 +19,5 @@ if __name__ == "__main__":
     mcts.load_tree()
     root = mcts.root_node
     G = nx.DiGraph()
-    tree = build_tree_recursive(G, "0", root)
-    visualize_tree(tree, save_path="results/tree.png")
+    build_tree_recursive(G, "0", root)
+    visualize_tree(G, save_path="results/tree.png")